Japanese scientists cage light

Breakthrough for quantum computing

Scientists have used silicon crystals to trap light and slow it down to the lowest speed ever recorded in the material. The breakthrough is a step towards light-based storage for quantum computers.

Researchers at Japanese telco NTT used man-made photonic crystals, which contain nanoscale holes, to achieve the feat. The cavity which controlled the light was less than ten millionths of a metre long.

The photon-trapping set-up slowed the light down to just 5.8 kilometres per second - 50,000 times less than the speed of light in a vacuum - by actually trapping it in the cavity for a nanosecond.

Last year, a team at Harvard "froze light" to demonstrate how photons could be used to bear information in an optical computer, replacing electrons. The Japanese research adds the ability to trap them for RAM-style memory.

The power to control light is seen as a key development for quantum information and communication, which promises a step change in computing power because of the greater number of states a quantum information carrier can take than in current simple electron-driven microprocessors.

Current early applications of quantum information technology centre around cryptography. More here.

The research is due to be reported in the January edition of the journal Nature Photonics. ®